There are four possible electrocardiographic rhythms in cardiac arrest: ventricular fibrillation (VF), pulseless ventricular tachycardia (VT), pulseless electrical activity (PEA), and asystole. VF is a disorganized electrical activity, while a pulseless VT produces an organized electrical activity. Both of these electrical states are incapable of producing sufficient blood flow. PEA is an organized electric rhythm that is characterized by an absence or insufficient mechanical ventricular activity to produce a detectable pulse. Asystole is an absence of ventricular electrical activity with or without atrial electric activity. The chances of survival decrease as the delay of defibrillation in VF and pulseless VT increases.1-2 Therefore, hospitals should develop a plan to reduce the interval between arrest and rapid defibrillation.3 Outcomes in defibrillation are also optimized if the interruptions between chest compressions are minimized. This has resulted in a significant improvement in the rate of survival to hospital discharge.4-10
Conversely, it is important to note that other advanced cardiac life support (ACLS) therapies, such as medical interventions and advanced airways, may improve the likelihood of return of spontaneous circulation (ROSC), but have not shown significant improvement in the rate of survival to hospital discharge.11-17 The key to rhythm-based management is that interruptions in cardiopulmonary resuscitation (CPR) should be as short as possible, giving way only to assess the rhythm, shock VF or pulseless VT if indicated, perform a pulse check when an organized rhythm is achieved or to place an airway.
The arrest rhythm frequently changes during the course of resuscitation, and management should be modified to the appropriate rhythm-based strategy. For example, the health care providers should be prepared to immediately defibrillate a cardiac arrest victim in asystole or PEA who converts into VF or pulseless VT during a rhythm check. The following describes the management of the cardiac arrest victim according to rhythm.
The way in which healthcare providers execute rhythm-based management will determine in part the outcome of the patient in cardiac arrest. In reality, there are far more unsuccessful resuscitative attempts than successful ones. Research continues to determine the best and most appropriate treatment modalities for victims of cardiac arrest.
Table 1. H’s and T’s
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